I need to make larger my submission option

I made a form because it is for my wedding. I mean, it is for my wedding guests to confirm their attendance. Therefore, I need 250 submissions available at least. Please, let me know it it is possible

It is possible to get 250 submissions or more. However, I checked your account and you're under Free plan user. The submission limit for Free user is 100 submissions only. You can upgrade your account to Bronze plan which can holds up to 1,000 submissions. After the event, you can downgrade your account back to Free user. 

Let us know if you need more clarifications or any questions. We'll be happy to assist you.